Liquid cooling of anodes in vacuum discharge tubes, more particularly x-ray tubes



Nov. 4, 1952 F.

LIQUID COOLING 0F ANODES REINIGER 2,617,057

IN VACUUM DISCHARGE TUBES, MORE P ICULARLY AY TUBES 'led oct. 195oINVENTOR. FRIEDRICH REINIGER AGENT the heated surface.

Patented Nov. 4, 1952 DISCHARGE. TUBES,

BiORE PARTICU- LARLY XLR-AY. TUBES Friedrich Reiniger,Hamburg-Wellingsbuttel, Germany, assignor to Hartford NationalBank andTrust Company, Hartford, Conn., as trustee Application .October 21,1950, Serial N'o. 191,349 In Germany October 311949 4 claims. (ci.sis-32.),

The invention relates to an X-raytube comprising a liquid-cooled anode.This method is adapted more particularly with X-ray tubes which areheavily loaded and are in use continuously for some time. Examplesoisuch uses arev therapeutic irradiations and examination of materials.

The heat produced in the anode is preferably transmitted to the liquidat an area closely behind the focus. It is common practice to supply theliquid in a space recessed in the anode body, the liquid flowing athighspeed along the sur-face to` be cooled.

In a further construction the liquid is passed through a channel whichis providedy in the material of the anodel in order toincrease thesurfacearea to be cooled, the pressure on the liquid becoming very high,when the liquid is also required to flow at high speed.

Intense cooling isobtained, when the liquid is projected through anozzleat high speed against that a greatly turbulent flow is produced and thatthe formation of a laminary layer which involves material increase inthermal resistance is substantially avoided. However, owing to thequantity of heat to be conducted away, the surface area to be cooled mayassume such great dimensions that the liquid from the'space between thenozzle-'and the surface to be cooled cannot be drained at suicient highspeed, so that the pressure dierence at the front and at the back of thenozzley decreases and is nor longer uniform throughout the surface area.In this caseV the spacing between the'nozzle' apertures will have to beincreased or the speed of the liquid flow will have to be decreased. Inthis case the use ofa. nozzle for the liquidsupply is not particularlyadvantageous over the use of a liquid flowing along the surface.

According to the invention, in anA X-ray tube having a liquid-cooledanode, the liquid-is passed in succession through two or' more nozzles,which are arrangedopposite different partsxof the surface to be cooled.With a view to securing the required quantity of liquid, the dimensionsand the distance from the surface to be: cooled may be such for eachnozzle that the pressure on the liquid supplied is distributed among thenozzles and only low losses of' pressureV occur along the course stillto be traversed by the liquid.

In order that the invention may be more clearly understood and readilycarried intoeiect, it. will now be described more fully with referenceto the accompanying drawing, in which Figs. 1

The advantage thereof is I use', a iiow offelectronsamoves from'. thecathode` 44 through the: aperturey 5 in the front rofV the anode 3. toa' plate of impact Ii, which isznadev ofY tungsten and is securedrto themetal anode. body. The anode 3f. is made of copper and is provided withahollow spacev L This space, contains a metal plug 8, which' .closestheY space 'I. toV the outside and which is: providedwith` a. bore 9. Y

which communicates with' a supply pipe Id for thezcooling liquid,.thedirection of flow of.V which is indicated by an arrow H. The plugS'extends.

tonear thebottom I2. of thel spaceY 1'... Referring to Fig. l thebore 9is widened atits end so as to. have .approximately the. same.; diameter'asthe plug and in frontzof the aperture provision is made of a nozzlelieonstituted byaat plate'y havingv small apertures. The cooling liquidis projected from these apertures. at a. speed against the surfacev I2.;fromwhichiis withdrawn the Vheat; produced. in; the impact plate. bythe' electron flowA and supplied by conductionof. the anode material.The liquid escapes.v from: the space: between the nozzle I3v and the.surface: l2 along. the edge andi passesv through a second nozzle I4;arranged opposite another partofithe surfaeexto hecooled andconstituted. by a: cillin-.- drical shell, which isV providedwith smallapertures.. The` liquid is. projected through the: apen'- tures;. againin: a iinely dividedlstatefbut kenerget ically' against 'part of. the;cylindrical wall. I5' of lthe hollow space l into.: the'anode'andthen'flows through the' space'between the plug 8: and this wall to theoutside through apertures I6 in the Wall portion t5 of the anode 3*. inthe direction of. arrows. Il.

Referring to'Fig. 2 the bore 9 is lesswidened'; so that thel nozzlev i3covers` a smaller portion of the surfacev I2. The liquid lescapes fromthe space between the nozzle I3 and the surface lf2' through an apertureI8 to a space I 9, which is recessedvin the plugv 8. A nozzley 20, whichthen allows the liquidI to pass, is constituted byfan' annular platewith/small' apertures which is :Ilush with the nozzle I3 and which isconnected to the plug along thev outer circumference, whereas along theinner` circumference` provision is" made of an upright edge 2l whichbears on the bottom of the space l. The liquid escapes from the spacebetween the nozzle 2i) and the bottom l2 and is then drained. Provisionmay be made of a third nozzle the construction of which is similar tothe nozzle i4 of Fig. l.

Owing to the successive disturbances produced in the liquid flow, sincethe latter passes in succession through two or more nozzles, the heattransfer to the liquid contacting with the surface to be cooled is notaffected when the surface area exceeds the size for which a singlenozzle is suicient. It is true that with an increase of the surface tobe cooled the required quantity of liquid increases, but the higherpressure required therefor is distributed among the various nozzleswithout incurring any loss of pressure owing to the increase inresistance of the liquid flow due to less favourable properties in thecase of a single nozzle and of increasing surface to be cooled.

What I claim is:

1. An X-ray tube comprising an envelope, a cathode, an anode comprisinga target of heat refractory metal facing the cathode, a body of goodheat conducting material backing said target and having a hollowrecessed portion to the rear of the target, a hollow plug fitting intosaid recessed portion, means to circulate a cooling medium over amaximum surface area of said recessed portion of said body comprising afirst perforated member having a plurality of openings therein formingwith said plug a rst chamber directly in back of the surface area of therecessed portion and forming a plurality of passages perpendicular to afirst portion of the surface area of said recessed portion whereby thecooling medium will flow with high turbulence over the rst portion ofthe surface area to be cooled without forming a laminar layer to effectmaximum heat transfer from said body to said cooling medium, asecond'perforated member having a plurality of openings therein andforming with said first surface portion and said rst perforated member asecond chamber directly in back of a second portion of the surface ofsaid recessed portion, said second perforated member providing aplurality of passages perpendicular to the second portion of the surfacearea of said recessed portion whereby the cooling medium after strikingsaid first surface portion is recovered and flows with high turbulenceoversaid second surface portion without forming a laminar layer toeffect further heat transfer from said body to said cooling medium.

2. An X-ray tube comprising an envelope, a cathode, an anode comprisinga target of heat refractory metal facing the cathode, a body of goodheat conducting material backing said target and having a hollowrecessed portion to the rear of the target, a hollow plug fitting intosaid recessed portion, means to circulate a cooling medium over amaximum surface area of said recessed portion of said body comprising afirst perforated member having a plurality of openings therein forrningwith said plug a first chamber directly in back of the surface area ofthe recessed portion and forming a plurality of passages perpendicularto a central portion of the surface area of said recessed portionwhereby the cooling medium will flow with high turbulence over thecentral surface portion of area to be cooled without forming a laminarlayer to effect maximum heat transfer from said body to said cooling nmedium, a second perforated member having a plurality of openingstherein and forming with said first surface portion and said firstperforated member a second chamber directly in back of a side portion ofsaid surface area and forming a plurality of passages perpendicular tothe side portion of the surface area of said recessed portion wherebythe cooling medium after striking said first surface portion isrecovered and flows with high turbulence over said second surfaceportion Without forming a laminar layer to effect further heat transferfrom said body to said cooling medium.

3. An X-ray tube comprising an envelope, a cathode, an anode comprisinga, target of heat refractory metal facing the cathode. a body of goodheat conducting material backing said target and having a hollowrecessed portion to the rear of the target, a hollow plug fitting intosaid recessed portion, means to circulate a cooling medium over amaximum surface area of said recessed portion of said body comprising afirst perforated member having a plurality of openings therein over theend of the plug and forming with said plug a first chamber directly inback of central portion of the surface area, said perforated memberforming a plurality of passages perpendicular to the central portion ofthe surface area of said recessed portion whereby the cooling mediumwill flow With high turbulence over the surface of said central surfaceportion without forming a laminar layer to effect maximum heat transferfrom said body to said cooling medium, a second perforated member havinga plurality of openings therein forming with said portion and said plugmember a second chamber communicating with said first chamber and whichis directly in back of a side portion of the said surface area to becooled adjacent said central surface portion, said second perforatedmember forming a plurality of passages perpendicular to the side surfaceportion of the surface area of said recessed portion whereby the coolingmedium after striking said central surface portion is recovered andflows with high turbulence over said side surface portion withoutforming a laminar layer to effect further heat transfer from said bodyto said cooling medium.

4. An X-ray tube comprising an envelope, a cathode, an anode comprisinga target of heat refractory metal facing the cathode, a body of goodheat conducting material backing said target and having a recessedportion to the rear of the target, a hollow plug fitting into therecessed portion of the body, the hollow plug having a conical internaltaper diverging towards the surface area of the recessed portion, meansto circulate a cooling medium over a maximum surface area of therecessed portion comprising a first perforated member having a pluralityof openings therein over the end of the plug and forming with said pluga first chamber directly in back of the surface area of the end of saidrecessed portion, said perforated member forming a plurality of passagesperpendicular to surface area of said recessed portion whereby thecooling medium will flow with the high turbulence over the surface ofsaid end surface portion without forming a laminal layer to effectmaximum heat transfer from said body to said cooling medium, a secondperforated member having a plurality of openings therein and formingwith the walls of the plug and the side surface portions of the recessedportion of said body a second chamber directly in back of the 6REFERENCES CITED The following references are of record in the rile ofthis ipatent:

Number UNITED STATES PATENTS Name Date Rowland Jan. 23, 1894 Spiro Dec.15, 1925 Niemann et a1 July 12, 1938 Findlay et a1. Mar. 24, 1942' Atleeet a1. Oct. 19, 1943

